GenAI Utils | Add metrics to LLMInvocations (#3891)

* add metrics to genai utils

* add Instruments class for GenAI metrics and refactor metric recording

* refactor: streamline metric payload handling in InvocationMetricsRecorder

* fix: grammar

* doc: added changelog

* fix: update version for semconvs

* Lint fixes

* Fix Nits, remove overly defensive code

* Add monotonic timing support for LLM invocation duration calculations

* small cleanups to types to simplify code

* cleanup test

* Simplify histogram duration time calculations

* Remove unused constants and helper function

* Refactor histogram creation to use standalone functions instead of a class

---------

Co-authored-by: aaronabbott <aaronabbott@google.com>

Author: keith-decker

util/opentelemetry-util-genai/CHANGELOG.md

@@ -12,6 +12,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3943](#3943))
 - Add more Semconv attributes to LLMInvocation spans. 
   ([https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3862](#3862))
+- Add metrics to LLMInvocation traces
+  ([https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3891](#3891))
 
 ## Version 0.2b0 (2025-10-14)
 

util/opentelemetry-util-genai/src/opentelemetry/util/genai/handler.py

@@ -60,20 +60,24 @@
 
 from __future__ import annotations
 
+import timeit
 from contextlib import contextmanager
 from typing import Iterator
 
 from opentelemetry import context as otel_context
+from opentelemetry.metrics import MeterProvider, get_meter
 from opentelemetry.semconv._incubating.attributes import (
     gen_ai_attributes as GenAI,
 )
 from opentelemetry.semconv.schemas import Schemas
 from opentelemetry.trace import (
+    Span,
     SpanKind,
     TracerProvider,
     get_tracer,
     set_span_in_context,
 )
+from opentelemetry.util.genai.metrics import InvocationMetricsRecorder
 from opentelemetry.util.genai.span_utils import (
     _apply_error_attributes,
     _apply_finish_attributes,
@@ -88,13 +92,35 @@ class TelemetryHandler:
     them as spans, metrics, and events.
     """
 
-    def __init__(self, tracer_provider: TracerProvider | None = None):
+    def __init__(
+        self,
+        tracer_provider: TracerProvider | None = None,
+        meter_provider: MeterProvider | None = None,
+    ):
         self._tracer = get_tracer(
             __name__,
             __version__,
             tracer_provider,
             schema_url=Schemas.V1_37_0.value,
         )
+        self._metrics_recorder: InvocationMetricsRecorder | None = None
+        meter = get_meter(__name__, meter_provider=meter_provider)
+        self._metrics_recorder = InvocationMetricsRecorder(meter)
+
+    def _record_llm_metrics(
+        self,
+        invocation: LLMInvocation,
+        span: Span | None = None,
+        *,
+        error_type: str | None = None,
+    ) -> None:
+        if self._metrics_recorder is None or span is None:
+            return
+        self._metrics_recorder.record(
+            span,
+            invocation,
+            error_type=error_type,
+        )
 
     def start_llm(
         self,
@@ -106,6 +132,9 @@ def start_llm(
             name=f"{GenAI.GenAiOperationNameValues.CHAT.value} {invocation.request_model}",
             kind=SpanKind.CLIENT,
         )
+        # Record a monotonic start timestamp (seconds) for duration
+        # calculation using timeit.default_timer.
+        invocation.monotonic_start_s = timeit.default_timer()
         invocation.span = span
         invocation.context_token = otel_context.attach(
             set_span_in_context(span)
@@ -118,10 +147,12 @@ def stop_llm(self, invocation: LLMInvocation) -> LLMInvocation:  # pylint: disab
             # TODO: Provide feedback that this invocation was not started
             return invocation
 
-        _apply_finish_attributes(invocation.span, invocation)
+        span = invocation.span
+        _apply_finish_attributes(span, invocation)
+        self._record_llm_metrics(invocation, span)
         # Detach context and end span
         otel_context.detach(invocation.context_token)
-        invocation.span.end()
+        span.end()
         return invocation
 
     def fail_llm(  # pylint: disable=no-self-use
@@ -132,11 +163,14 @@ def fail_llm(  # pylint: disable=no-self-use
             # TODO: Provide feedback that this invocation was not started
             return invocation
 
+        span = invocation.span
         _apply_finish_attributes(invocation.span, invocation)
-        _apply_error_attributes(invocation.span, error)
+        _apply_error_attributes(span, error)
+        error_type = getattr(error.type, "__qualname__", None)
+        self._record_llm_metrics(invocation, span, error_type=error_type)
         # Detach context and end span
         otel_context.detach(invocation.context_token)
-        invocation.span.end()
+        span.end()
         return invocation
 
     @contextmanager
@@ -166,6 +200,7 @@ def llm(
 
 def get_telemetry_handler(
     tracer_provider: TracerProvider | None = None,
+    meter_provider: MeterProvider | None = None,
 ) -> TelemetryHandler:
     """
     Returns a singleton TelemetryHandler instance.
@@ -174,6 +209,9 @@ def get_telemetry_handler(
         get_telemetry_handler, "_default_handler", None
     )
     if handler is None:
-        handler = TelemetryHandler(tracer_provider=tracer_provider)
+        handler = TelemetryHandler(
+            tracer_provider=tracer_provider,
+            meter_provider=meter_provider,
+        )
         setattr(get_telemetry_handler, "_default_handler", handler)
     return handler

util/opentelemetry-util-genai/src/opentelemetry/util/genai/instruments.py

@@ -0,0 +1,54 @@
+from opentelemetry.metrics import Histogram, Meter
+from opentelemetry.semconv._incubating.metrics import gen_ai_metrics
+
+_GEN_AI_CLIENT_OPERATION_DURATION_BUCKETS = [
+    0.01,
+    0.02,
+    0.04,
+    0.08,
+    0.16,
+    0.32,
+    0.64,
+    1.28,
+    2.56,
+    5.12,
+    10.24,
+    20.48,
+    40.96,
+    81.92,
+]
+
+_GEN_AI_CLIENT_TOKEN_USAGE_BUCKETS = [
+    1,
+    4,
+    16,
+    64,
+    256,
+    1024,
+    4096,
+    16384,
+    65536,
+    262144,
+    1048576,
+    4194304,
+    16777216,
+    67108864,
+]
+
+
+def create_duration_histogram(meter: Meter) -> Histogram:
+    return meter.create_histogram(
+        name=gen_ai_metrics.GEN_AI_CLIENT_OPERATION_DURATION,
+        description="Duration of GenAI client operation",
+        unit="s",
+        explicit_bucket_boundaries_advisory=_GEN_AI_CLIENT_OPERATION_DURATION_BUCKETS,
+    )
+
+
+def create_token_histogram(meter: Meter) -> Histogram:
+    return meter.create_histogram(
+        name=gen_ai_metrics.GEN_AI_CLIENT_TOKEN_USAGE,
+        description="Number of input and output tokens used by GenAI clients",
+        unit="{token}",
+        explicit_bucket_boundaries_advisory=_GEN_AI_CLIENT_TOKEN_USAGE_BUCKETS,
+    )

util/opentelemetry-util-genai/src/opentelemetry/util/genai/metrics.py

@@ -0,0 +1,98 @@
+"""Helpers for emitting GenAI metrics from LLM invocations."""
+
+from __future__ import annotations
+
+import timeit
+from numbers import Number
+from typing import Dict, Optional
+
+from opentelemetry.metrics import Histogram, Meter
+from opentelemetry.semconv._incubating.attributes import (
+    gen_ai_attributes as GenAI,
+)
+from opentelemetry.trace import Span, set_span_in_context
+from opentelemetry.util.genai.instruments import (
+    create_duration_histogram,
+    create_token_histogram,
+)
+from opentelemetry.util.genai.types import LLMInvocation
+from opentelemetry.util.types import AttributeValue
+
+
+class InvocationMetricsRecorder:
+    """Records duration and token usage histograms for GenAI invocations."""
+
+    def __init__(self, meter: Meter):
+        self._duration_histogram: Histogram = create_duration_histogram(meter)
+        self._token_histogram: Histogram = create_token_histogram(meter)
+
+    def record(
+        self,
+        span: Optional[Span],
+        invocation: LLMInvocation,
+        *,
+        error_type: Optional[str] = None,
+    ) -> None:
+        """Record duration and token metrics for an invocation if possible."""
+        if span is None:
+            return
+
+        token_counts: list[tuple[int, str]] = []
+        if invocation.input_tokens is not None:
+            token_counts.append(
+                (
+                    invocation.input_tokens,
+                    GenAI.GenAiTokenTypeValues.INPUT.value,
+                )
+            )
+        if invocation.output_tokens is not None:
+            token_counts.append(
+                (
+                    invocation.output_tokens,
+                    GenAI.GenAiTokenTypeValues.OUTPUT.value,
+                )
+            )
+
+        attributes: Dict[str, AttributeValue] = {
+            GenAI.GEN_AI_OPERATION_NAME: GenAI.GenAiOperationNameValues.CHAT.value
+        }
+        if invocation.request_model:
+            attributes[GenAI.GEN_AI_REQUEST_MODEL] = invocation.request_model
+        if invocation.provider:
+            attributes[GenAI.GEN_AI_PROVIDER_NAME] = invocation.provider
+        if invocation.response_model_name:
+            attributes[GenAI.GEN_AI_RESPONSE_MODEL] = (
+                invocation.response_model_name
+            )
+
+        # Calculate duration from span timing or invocation monotonic start
+        duration_seconds: Optional[float] = None
+        if invocation.monotonic_start_s is not None:
+            duration_seconds = max(
+                timeit.default_timer() - invocation.monotonic_start_s, 0.0
+            )
+
+        span_context = set_span_in_context(span)
+        if error_type:
+            attributes["error.type"] = error_type
+
+        if (
+            duration_seconds is not None
+            and isinstance(duration_seconds, Number)
+            and duration_seconds >= 0
+        ):
+            self._duration_histogram.record(
+                duration_seconds,
+                attributes=attributes,
+                context=span_context,
+            )
+
+        for token_count, token_type in token_counts:
+            self._token_histogram.record(
+                token_count,
+                attributes=attributes | {GenAI.GEN_AI_TOKEN_TYPE: token_type},
+                context=span_context,
+            )
+
+
+__all__ = ["InvocationMetricsRecorder"]

util/opentelemetry-util-genai/src/opentelemetry/util/genai/types.py

@@ -123,6 +123,12 @@ class LLMInvocation:
     max_tokens: int | None = None
     stop_sequences: list[str] | None = None
     seed: int | None = None
+    monotonic_start_s: float | None = None
+    """
+    Monotonic start time in seconds (from timeit.default_timer) used
+    for duration calculations to avoid mixing clock sources. This is
+    populated by the TelemetryHandler when starting an invocation.
+    """
 
 
 @dataclass